1. Field of the Invention
The present invention relates to polycondensation compounds derived from 2,4-diamino-6-hydroxy-1,3,5-triazine (ameline).
More particularly the present invention relates to ameline derivatives and to the use thereof for the preparation of self-extinguishing polymeric compositions, based on thermoplastic polymers or polymers endowed with elastomeric properties, expecially olefinic polymers and copolymers, in combination with phosphates and/or phosphonates of ammonium or of amine.
2. Discussion of the Background
There are various solutions known in the art to reduce or to remove the combustibility of polymers. Some of these solutions are based on the use of metal compounds, especially antimony, bismuth or arsenic, in combination with organic compounds that are partially halogenated and thermally unstable, such as chlorinated paraffinic waxes.
Other solutions are based on the use of substances able to produce intumescence. Formulations of the intumescent type generally consist of the polymer and of at least three main additives: one essentially phosphorated, the purpose of which is to form, on combustion, an impermeable, semisolid, vitreous layer, essentially consisting of polyphosphoric acid, and to activate the process for the formation of the intumescence; a second containing nitrogen which acts as foaming agent; and a third one containing carbon which acts as carbon donor for the formation of an insulating cellular carbon layer (char) between the polymer and the flame.
Examples of intumescent formulations of this type are those described in U.S. Pat. No. 3,810,862 (Phillips Petroleum Co.) based on melamine, pentaerythritol and ammonium polyphosphate, U.S. Pat. No. 4,727,102 (Vamp s.r.l.) consisting of isocyanuric acid and ammonium polyphosphate, and in the published patent appln. WO 85/05626 (Plascoat U.K. Limited) consisting of several phosphorus and nitrogen compounds, among which, in particular, are a combination of melamine phosphate, pentaerythritol and ammonium polyphosphate.
More recent formulations have used, together with an organic or inorganic phosphorous compound, an organic compound containing nitrogen, generally an aminoplastic resin obtained by condensing urea, melamine or dicyanodiamide with formaldehyde.
Examples of formulations consisting of two additives are those reported in U.S. Pat. No. 4,504,610 (Montedison S.p.A.), based on oligomeric derivatives of 1,3,5-triazine and ammonium polyphosphate, and European Pat. 14.463 (Montedison S.p.A.), based on organic compounds selected from benzylguanamine and reaction products between aldehydes and several nitrogenous cyclic compounds, in particular benzylguanamine-formaldehyde copolymers, and ammonium polyphosphate.
It is also possible to obtain self-extinguishing compositions using monocomponent additives, containing in the organic molecule both nitrogen and phosphorus, as described in U.S. Pat. No. 4,201,705 (Borg-Warner Corp.).
These intumescent retarding systems give to the polymer containing them the property of forming a carbon residue as a result of a fire or application of a flame. Retarder systems of this type show many advantages: absence of corrosion phenomena in apparatus in which polymers are processed, lower emission of smoke in comparison with systems containing metal compounds and halogenated hydrocarbons, and overall the possibility of giving satisfactory antiflame properties to polymers, using a lower amount of additive and therefore without an excessive decay of mechanical properties of polymers themselves.